1. Field of the Invention
The present invention relates to a swivel work machine such as a backhoe.
In the following description relating to left and right opposed sides of a swivel table or its swivel base plate under a straight traveling condition of a machine body, either one side thereof will be referred to as “one lateral side” or “a first lateral side” and the other side will be referred to as “the other lateral side” or “a second lateral side”, respectively.
2. Description of the Related Art
In a conventional backhoe as an example of a swivel work machine, a swivel table is mounted on a traveling unit to be pivotable about a vertical swivel axis. At a front portion of the swivel table, there is mounted a work implement (excavator) having a swing bracket, a boom, an arm, a bucket, etc (see JP-A-2004-268799 or its corresponding EP 1 457 364 A1, for example).
The swivel table includes a swivel base plate which is mounted on a track frame of the traveling unit to be pivotable about a swivel axis via a swivel bearing. To the front of this swivel base plate, there are provided a pair of upper and lower support brackets comprised of plate members. To the front portions of these upper and lower support brackets, a swing bracket is pivotally connected to be pivotable about a vertical axis. Further, to this swing bracket, a base portion of a boom is connected to be pivotable about a right/left axis and a base portion of an arm is connected to the leading end of the boom to be pivotable about a right/left axis. And, at the leading end of this arm, a bucket is connected to be pivotable about a right/left axis.
Further, on the swivel base plate, there are fixedly welded a pair of left and right vertical ribs comprised of plate members extending rearward from the support brackets, with the lower support bracket being fixedly welded to the swivel base plate, front ends of the left and right vertical ribs being inserted between and fixedly welded to the upper and lower support brackets, the portions of the upper and lower support brackets pivotally supporting the swing bracket projecting forwardly from the swivel base plate.
Also, the upper and lower support brackets are disposed with an offset to one lateral side (in this case, to the right side) from the right/left center, and a driver's seat is disposed at a substantially fore-and-aft center position upwardly of the swivel table, with an offset to the other lateral side (in this case, to the left side) from the right/left center. Downwardly of the driver's seat, there is provided a step forming an upper wall of the swivel table. On this step, there is mounted a cabin forming the driver's seat and a driver's cab. The left-side vertical rib and the base portions of the upper and lower support brackets (the rear portions) are disposed under the step to be accommodated within the swivel table.
In the conventional backhoe described above, in order to ensure sufficient strength for supporting the excavator, the front end portions of the left and right vertical ribs to be inserted between the upper and lower support brackets are provided with an extended vertical width. However, as the base portions of the upper and lower support brackets are disposed downwardly of the step, it was difficult to form the bottom of the cabin lower for the purpose of e.g. improved stability.